Tracing: Add more DCHECKS to get more info on recent test flakiness

base/trace_event/trace_log.cc

Index: base/trace_event/trace_log.cc
diff --git a/base/trace_event/trace_log.cc b/base/trace_event/trace_log.cc
index 872cd172b2b7310ef81b40befb90c06a3e7d5a90..a0a6aeecf23392002e9bdd629ff0162c818aac27 100644
--- a/base/trace_event/trace_log.cc
+++ b/base/trace_event/trace_log.cc
@@ -174,6 +174,7 @@ void MakeHandle(uint32_t chunk_seq,
   DCHECK(chunk_seq);
   DCHECK(chunk_index <= TraceBufferChunk::kMaxChunkIndex);
   DCHECK(event_index < TraceBufferChunk::kTraceBufferChunkSize);
+  DCHECK(chunk_index <= std::numeric_limits<uint16_t>::max());
   handle->chunk_seq = chunk_seq;
   handle->chunk_index = static_cast<uint16_t>(chunk_index);
   handle->event_index = static_cast<uint16_t>(event_index);
@@ -1608,6 +1609,10 @@ TraceEvent* TraceLog::GetEventByHandleInternal(TraceEventHandle handle,
   if (!handle.chunk_seq)
     return NULL;
 
+  DCHECK(handle.chunk_seq);
+  DCHECK(handle.chunk_index <= TraceBufferChunk::kMaxChunkIndex);
+  DCHECK(handle.event_index < TraceBufferChunk::kTraceBufferChunkSize);
+
   if (thread_local_event_buffer_.Get()) {
     TraceEvent* trace_event =
         thread_local_event_buffer_.Get()->GetEventByHandle(handle);